/*
 * Copyright (c) Baidu Inc. All rights reserved.
 * 
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package com.baidu.bjf.remoting.protobuf.utils;

import java.io.IOException;
import java.io.Writer;

/**
 * A character stream that collects its output in a string buffer, which can then be used to construct a string.
 * <p>
 * Closing a <tt>StringWriter</tt> has no effect. The methods in this class can be called after the stream has been
 * closed without generating an <tt>IOException</tt>.
 * 
 * @author xiemalin
 * @since 1.12.0
 */

public class StringBuilderWriter extends Writer {

    /** The buf. */
    private StringBuilder buf;

    /**
     * Create a new string writer using the default initial string-buffer size.
     */
    public StringBuilderWriter() {
        buf = new StringBuilder();
        lock = buf;
    }

    /**
     * Create a new string writer using the specified initial string-buffer size.
     *
     * @param initialSize The number of <tt>char</tt> values that will fit into this buffer before it is automatically
     *            expanded
     *
     * @throws IllegalArgumentException If <tt>initialSize</tt> is negative
     */
    public StringBuilderWriter(int initialSize) {
        if (initialSize < 0) {
            throw new IllegalArgumentException("Negative buffer size");
        }
        buf = new StringBuilder(initialSize);
        lock = buf;
    }

    /**
     * Write a single character.
     *
     * @param c the c
     */
    public void write(int c) {
        buf.append((char) c);
    }

    /**
     * Write a portion of an array of characters.
     *
     * @param cbuf Array of characters
     * @param off Offset from which to start writing characters
     * @param len Number of characters to write
     */
    public void write(char cbuf[], int off, int len) {
        if ((off < 0) || (off > cbuf.length) || (len < 0) || ((off + len) > cbuf.length) || ((off + len) < 0)) {
            throw new IndexOutOfBoundsException();
        } else if (len == 0) {
            return;
        }
        buf.append(cbuf, off, len);
    }

    /**
     * Write a string.
     *
     * @param str the str
     */
    public void write(String str) {
        buf.append(str);
    }

    /**
     * Write a portion of a string.
     *
     * @param str String to be written
     * @param off Offset from which to start writing characters
     * @param len Number of characters to write
     */
    public void write(String str, int off, int len) {
        buf.append(str.substring(off, off + len));
    }

    /**
     * Appends the specified character sequence to this writer.
     *
     * <p>
     * An invocation of this method of the form <tt>out.append(csq)</tt> behaves in exactly the same way as the
     * invocation
     *
     * <pre>
     * out.write(csq.toString())
     * </pre>
     *
     * <p>
     * Depending on the specification of <tt>toString</tt> for the character sequence <tt>csq</tt>, the entire sequence
     * may not be appended. For instance, invoking the <tt>toString</tt> method of a character buffer will return a
     * subsequence whose content depends upon the buffer's position and limit.
     *
     * @param csq The character sequence to append. If <tt>csq</tt> is <tt>null</tt>, then the four characters
     *            <tt>"null"</tt> are appended to this writer.
     *
     * @return This writer
     *
     * @since 1.5
     */
    public StringBuilderWriter append(CharSequence csq) {
        if (csq == null)
            write("null");
        else
            write(csq.toString());
        return this;
    }

    /**
     * Appends a subsequence of the specified character sequence to this writer.
     *
     * <p>
     * An invocation of this method of the form <tt>out.append(csq, start,
     * end)</tt> when <tt>csq</tt> is not <tt>null</tt>, behaves in exactly the same way as the invocation
     *
     * <pre>
     * out.write(csq.subSequence(start, end).toString())
     * </pre>
     *
     * @param csq The character sequence from which a subsequence will be appended. If <tt>csq</tt> is <tt>null</tt>,
     *            then characters will be appended as if <tt>csq</tt> contained the four characters <tt>"null"</tt>.
     *
     * @param start The index of the first character in the subsequence
     *
     * @param end The index of the character following the last character in the subsequence
     *
     * @return This writer
     *
     * @throws IndexOutOfBoundsException If <tt>start</tt> or <tt>end</tt> are negative, <tt>start</tt> is greater than
     *             <tt>end</tt>, or <tt>end</tt> is greater than <tt>csq.length()</tt>
     *
     * @since 1.5
     */
    public StringBuilderWriter append(CharSequence csq, int start, int end) {
        CharSequence cs = (csq == null ? "null" : csq);
        write(cs.subSequence(start, end).toString());
        return this;
    }

    /**
     * Appends the specified character to this writer.
     *
     * <p>
     * An invocation of this method of the form <tt>out.append(c)</tt> behaves in exactly the same way as the invocation
     *
     * <pre>
     * out.write(c)
     * </pre>
     *
     * @param c The 16-bit character to append
     *
     * @return This writer
     *
     * @since 1.5
     */
    public StringBuilderWriter append(char c) {
        write(c);
        return this;
    }

    /**
     * Return the buffer's current value as a string.
     *
     * @return the string
     */
    public String toString() {
        return buf.toString();
    }

    /**
     * Gets the buffer.
     *
     * @return the buffer
     */
    public StringBuilder getBuffer() {
        return buf;
    }

    /**
     * Flush the stream.
     */
    public void flush() {
    }

    /**
     * Closing a <tt>StringWriter</tt> has no effect. The methods in this class can be called after the stream has been
     * closed without generating an <tt>IOException</tt>.
     *
     * @throws IOException Signals that an I/O exception has occurred.
     */
    public void close() throws IOException {
    }

}
